The Effect of Longitudinal Core Flow on Trailing Vortex Stability

2014 ◽  
Author(s):  
Amir Allaf-Akbari ◽  
A. Gordon L. Holloway ◽  
Joseph Hall
Keyword(s):  
Experimental Study ◽  
Velocity Field ◽  
Kinetic Energy ◽  
Vortex Core ◽  
Vortex Generator ◽  
Core Flow ◽  
Vortex Stability ◽  
Vorticity Distribution ◽  
Air Jet ◽  
Jet Velocities

The current experimental study investigates the effect of longitudinal core flow on the formation and structure of a trailing vortex. The vortex is generated using four airfoils connected to a central hub through which a jet flow is added to the vortex core. Time averaged vorticity, circumferential velocity, and turbulent kinetic energy are studied. The statistics of vortex wandering are identified and corrections applied to the vorticity distribution. The vortex generator used in this study was built on the basis of the design described by Beninati et al. [1]. It uses four NACA0012 airfoils connected to a central hub. The wings orientation can be adjusted such that each contributes to a strong trailing vortex on the center of the test section. The vortex generator also had the capability to deliver an air jet directed longitudinally through a hole in the hub at the joint of the airfoils. Tests were done without the jet and with the air jet at jet velocities of 10 and 20 m/s. Planar PIV was used to measure the velocity field in the vicinity of the vortex core. The measurements were taken at 3 chords behind the vortex generator.

EXPERIMENTAL STUDY OF DRIFT OBJECTS USING SPATIOTEMPORAL DATA UNDER COMPLEX VELOCITY FIELD

2020 ◽  
Vol 76 (2) ◽  
pp. I_313-I_318
Author(s):  
Yu CHIDA ◽  
Nobuki FUKUI ◽  
Nobuhito MORI ◽  
Tomohiro YASUDA ◽  
Takashi YAMAMOTO
Keyword(s):  
Experimental Study ◽  
Velocity Field ◽  
Spatiotemporal Data ◽  
Complex Velocity

Experimental study of thermal processes in gaseous methane at its natural convection

2021 ◽  
Author(s):  
V.A. Altunin ◽  
K.V. Altunin ◽  
M.R. Abdullin ◽  
M.R. Chigarev ◽  
I.N. Aliev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Power Plants ◽  
New Technologies ◽  
New Technology ◽  
Liquid Hydrocarbon ◽  
Thermal Processes ◽  
Rocket Engines ◽  
Air Jet ◽  
Single Use

The paper discovers the reasons for the transfer of single-use or reusable ground, air, aerospace, and space-based engines and power plants from liquid hydrocarbon fuels and coolers to gaseous fuels, or rather, to liquefied natural gas methane. The study gives specific examples of creating a new technology and using methane fuel and fuel in the existing units; lists the classes of methane engines and power plants, among which the main ones being piston engines and internal combustion power plants, air-jet engines and power plants, liquid propellant rocket engines and power plants. Findings of research show that it is necessary to experimentally study gaseous methane, so that it could be effectively used in advanced single-use or reusable ground, air, aerospace and space-based engines and power plants, and their features should be taken into account when designing and developing new technologies. The study introduces the results of the experimental study of thermal processes in gaseous methane during its natural convection, describes the experimental base in detail, as well as the procedure for conducting experiments, and develops methods for calculating the heat transfer coefficient to gaseous methane relying on the research results.

scholarly journals ON APPLICABILITY OF ADDITIVE TECHNOLOGY IN PRODUCING NOZZLES FOR JET NOISE INVESTIGATIONS

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 180-184 ◽  
Author(s):  
Igor Khramtsov ◽  
Evgeniya Cherenkova ◽  
Vadim Palchikovskiy ◽  
Oleg Kustov
Keyword(s):  
Sound Pressure ◽  
Small Diameter ◽  
Jet Noise ◽  
Additive Technology ◽  
Noise Radiation ◽  
Fused Deposition ◽  
Air Jet ◽  
Power Spectral ◽  
Noise Measurements ◽  
Jet Velocities

The split-type conical nozzles with replaceable exit sections with diameters of 30, 40 and 50 mm were designed and produced from steel by machine turning. In addition, the replaceable output parts of the nozzles with the same diameters were produced by additive technology (fused deposition manufacturing) from ABS plastic. In the acoustic anechoic chamber, the noise measurements of a single-stream cold air jet for all the nozzles at jet velocities in the range of 0.3-0.7 Mach numbers were carried out. The noise measurements were performed on distance of 2 m from the center of the nozzle exit section at angles from 30 to 105o. For different directions of noise radiation and different velocities of the jet, the power spectral density and overall sound pressure level were determined. The obtained results demonstrates that the jet noise for nozzles with diameter of 40 and 50 mm from steel and ABS plastic differs by no more than 1 dB, which is within the measurement error for these types of experiments. The nozzles with diameter 30 mm have a higher difference in noise, which can be explained by the more sensitivity of a nozzle with a small diameter to the deviations of geometric parameters when it produced by additive technology.

Noise Propagation Through Helicopter Gearbox Support Struts—An Experimental Study

1998 ◽  
Vol 120 (3) ◽  
pp. 695-704 ◽  
Author(s):  
M. J. Brennan ◽  
S. J. Elliott ◽  
K. H. Heron
Keyword(s):  
Experimental Study ◽  
Kinetic Energy ◽  
Flexural Vibration ◽  
Dominant Mode ◽  
Analytical Models ◽  
Longitudinal Motion ◽  
Transmission Path ◽  
Modes Of Vibration ◽  
The Subject ◽  
Lateral Behavior

A dominant source of noise in a helicopter cabin is the meshing of the gears in the main rotor gearbox. The main structural noise transmission path from this gearbox to the cabin is through the gearbox support struts, and this is the transmission path which is the subject of this paper. An experimental study is described which quantifies the way in which vibration propagates through one of these struts and the experimental results are interpreted with the aid of some simple analytical models. The contribution of the various modes of vibration to the transmission of the structure-borne noise is quantified by calculating the kinetic energy of the receiving structure from measured data. The results show that although the dominant mode of vibration is longitudinal, flexural resonances occur at some frequencies, and the contribution of the flexural vibration to the kinetic energy of the receiving structure at these frequencies can be comparable with that due to the longitudinal motion. It is demonstrated that the lateral behavior of the strut is dependent upon the static loading but the longitudinal behavior is relatively insensitive to this loading.

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